Under normal physiological conditions, during sleep, body temperature drops and resistance to bacteria and viruses also drops because metabolism of a human body slows down. If a person is not well tucked up during sleep, the person is extremely likely to catch a disease such as cold. Resistance of a child is poorer than resistance of an adult. Therefore, if a child kicks off a quilt during sleep and a parent does not tuck up the child well in time, the child is more likely to catch a cold.
An implementation process of an existing quilt-kicking prevention system is, before sleeping, a child wears a device on which a light sensor is installed; when a quilt is kicked off, intensity of light received by the light sensor becomes greater, and in this case, the quilt-kicking prevention system gives a sound alarm to remind a parent to tuck the child up.
An implementation process of another existing quilt-kicking prevention system is, before sleeping, a child wears a device on which a thermistor sensor, a differential amplifier, and a dedicated frequency modulation (FM) transceiver circuit are installed; when a quilt is kicked off, a resistance value of the thermistor sensor changes; the differential amplifier is used to start an encoder and drive a dedicated FM transmitter; the FM transmitter transmits a signal to an FM receiver at a parent end; and a device at the parent end starts a decoder, and makes a prompt sound to remind the parent to tuck the child up.
However, in the foregoing system in which the light sensor is used, the light sensor cannot normally alarm in extremely strong light (in daytime in which luminance is greater than 10000 luxes) or extremely weak light (at night without illumination in which luminance is less than 20 luxes). Consequently, the system is limited. If a reminding sound of the device is extremely low, the parent cannot be reminded. If a reminding sound is extremely loud, the child in sleep is likely to be awoken and sleep of the child is affected. In the foregoing system in which the thermistor sensor, the differential amplifier, and the dedicated FM transceiver circuit are used, the thermistor sensor that uses the differential amplifier varies within a large range. Consequently, a variation of an absolute temperature value cannot be precisely measured, a false alarm is prone to be caused, and use of the dedicated FM transceiver device leads to poor convenience, high costs, and large power consumption.